IMCA mechanical calculator
Version Française 
WikipédiA 
Inside  Operation  Add and Subtract  Multiply and Divide  Square root 
This calculator can perform the four basic operations :

Cleaning the machine. 

Note  Actions  Operand A/B  Counter D  Accumulator C 
Clear all  F E L  0000000000 
00000000 
0000000000000 
Set first number and add it to the accumulator  B=1524 K+  0000001524 
00000001 
0000000001524 
Set second number and add it!  L B=97 K+  0000000097 
00000002 
0000000001621 
Note  Actions  Operand A/B  Counter D  Accumulator C 
Clear all, comma to second digit  F E L M2  0000000000 
00000000 
0000000000000 
Set first number and add it to the accumulator  B=2014 K+  0000002014 
00000001 
0000000002014 
Set second number and substract it!  L B=1966 K  0000001966 
00000000 
0000000000048 
Note  Actions  Operand A/B  Counter D  Accumulator C 
Clear all  F E L  0000000000 
00000000 
0000000000000 
Set first number and add it 4 times to the accumulator  B=365 K+ K+ K+ K+  0000000365 
00000004 
0000000001460 
Shift right to the tens, and add the number twice to the accumulator  I K+ K+  0000000365 
00000024 
0000000008760 
Note  Actions  Operand A/B  Counter D  Accumulator C 
Clear all, comma to third digit for C and D  F E L M3  0000000000 
00000000 
0000000000000 
Set first number, shift carrier 3 positions to the right, add it to the accumulator  B=22 I I I K+  0000000022 
00001000 
0000000022000 
Reset counter and set the divisor  F+ E B=7  0000000007 
00000000 
0000000022000 
Substract 7 from 22 as many times as possible (*), shift left one digit  K K K J  0000000007 
00003000 
0000000001000 
Substract 7 from 10 as many times as possible, shift left one digit  K J  0000000007 
00003100 
0000000000300 
Substract 7 from 30 as many times as possible, shift left one digit  K K K K J  0000000007 
00003140 
0000000000020 
Substract 7 from 20 as many times as possible, shift left one digit  K K J  0000000007 
00003142 
0000000000006 
02 15.40We'll start working on the first block, the 2. On my IMCA, to get a good precision, place the carrier to have the arrow pointing at the 7th digit in the counter D. The, we'll get 6 or 7 digits for the square root acording to the number of digits in the first block.
Note  Actions  Operand A/B  Counter D  Accumulator C 
Clear all, columns B7B4 we program the value and send it to the accumulatorr  F E L M3 B=2154 K+  0002154000 
01000000 
2154000000000 
Clear the counter, column of the first block (B7) start with 1  F+ E L B=1  0001000000 
00000000 
2154000000000 
Substract the odd numbers in serie until a bell ring, then turn back once, decrement B and move carrier left!  B=1 K B=3 K ♪ K+ ♪ B=2 J  0002000000 
01000000 
1154000000000 
Columns B7B6 program the next odd number, 21, Substract the odd numbers in serie until a bell ring, then turn back once, decrement B and move carrier left!  B=21 K B=23 K B=25 K B=27 K B=29 K ♪ K+ ♪ B=28 J  0002800000 
01400000 
0194000000000 
Columns B7B5 program the next odd number, 281, Substract the odd numbers in serie until a bell ring, then turn back once, decrement B and move carrier left!  B=281 K B=283 K B=285 K B=287 K B=289 K B=291 K B=293 K ♪ K+ ♪ B=292 J  0002920000 
01460000 
0022400000000 